Modular optical cross-connect architecture with optical wavelength switching

Abstract

An optical cross-connect node architecture interfaces plural optical fiber input and output links, each link containing plural wavelength channels. In one embodiment, the input links are connected to a single optical coupler, or alternatively, to an associated one of plural optical couplers. Pairs of tunable optical filters and optical wavelength converters are each connected to an output port of the optical coupler, or to each of the plural optical couplers, and perform wavelength channel routing and switching in the wavelength domain, i.e., without the need for any optical space switch. In other embodiments, an additional input wavelength converter is connected to each input fiber link to convert the plural wavelength channels on each link to different, noninterferring wavelengths. This prevents wavelength contention in the optical coupler to which the input wavelength converters are connected. New fiber links may be added in modular fashion without significant impact on the pre-existing optical cross-connect structure. Similarly, new wavelength channels may also be multiplexed onto existing fibers to provide wavelength modularity without having to reconfigure the node.

What is claimed is: 
     
       1. A single stage optical cross-connect node for routing and switching wavelength communications channels at high speed, the single stage comprising: optical fiber input links and output links, each link containing plural wavelength channels;   optical splitters, each optical splitter coupled to a corresponding one of the input links;   optical star couplers coupled to each of the optical splitters, each optical star coupler receiving all wavelength channels from all of the input links;   tunable optical filters each connected to one of the optical star couplers for selecting any one of the input wavelength channels received on any of the input links;   optical wavelength converters each corresponding and connected to one of tunable optical filters for translating the selected wavelength channel to a different wavelength channel; and   optical combiners for combining selected wavelength channels generated by the wavelength converters onto corresponding optical fiber output links,   wherein the optical splitters, optical star couplers, tunable optical filters, optical wavelength converters, and optical combiners are included in the single stage.   
     
     
       2. The optical cross-connect node in claim 1, wherein the wavelength channels are switched in the optical cross-connect node without a space switch. 
     
     
       3. The optical cross connect node in claim 1, wherein the wavelength converters are four wave mixing semiconductor optical amplifiers. 
     
     
       4. The optical cross-connect node in claim 1, wherein the optical cross-connect is connected to an electronic cross-connect through each of the optical couplers. 
     
     
       5. The optical cross-connect node in claim 1, wherein one wavelength channel is routed by plural tunable filters to plural output fiber links. 
     
     
       6. The optical cross-connect node in claim 5, wherein the one wavelength channel routed to plural output fiber links contains analog signals. 
     
     
       7. An optical cross-connect node for routing and switching wavelength communications channels at high speed, comprising: optical fiber input links and output links, each link containing plural wavelength channels;   optical couplers each receiving wavelength channels from the input links;   tunable optical filters each connected to one of the optical couplers for selecting a wavelength channel;   optical wavelength converters each corresponding and connected to one of tunable optical filters for translating the selected wavelength channel to a different wavelength channel; and   optical combiners for combining selected wavelength channels generated by the wavelength converters onto corresponding optical fiber output links,   wherein a new fiber link or a new wavelength channel is added to the optical cross-connect node without disabling the optical cross-connect node.   
     
     
       8. An optical cross-connect node for routing and switching wavelength communications channels at high speed, comprising: optical fiber input links and output links, each link containing plural wavelength channels;   optical couplers each receiving wavelength channels from the input links;   tunable optical filters each connected to one of the optical couplers for selecting a wavelength channel;   optical wavelength converters each corresponding and connected to one of tunable optical filters for translating the selected wavelength channel to a different wavelength channel; and   optical combiners for combining selected wavelength channels generated by the wavelength converters onto corresponding optical fiber output links,   wherein one of the fiber links, optical converters, tunable optical filters, wavelength converters, or optical combiners is repaired without disabling the optical cross-connect node.   
     
     
       9. An optical cross-connect node for routing and switching wavelength communications channels at high speed, comprising: optical fiber input links and output links each containing a comb of plural wavelength channels;   input wavelength converters, each connected to one of the input links being capable of converting a comb of plural wavelength channels to another comb of wavelength channels;   optical couplers each receiving wavelength channels from the input links;   tunable optical filters each connected to one of the optical couplers for selecting a wavelength channel;   output optical wavelength converters each connected to a corresponding tunable optical filter for converting the selected wavelength channel to a different wavelength channel; and   optical combiners combining wavelength channels generated by some of the wavelength converters onto corresponding ones of the optical fiber output links.   
     
     
       10. The optical cross-connect node of claim 9, wherein the input wavelength converters selectively convert combs of wavelength channels on each input fiber link to different combs of wavelength channels to avoid wavelength contentions in the optical couplers. 
     
     
       11. The optical cross-connect node of claim 10, wherein the output wavelength converters restore the wavelengths selected by the tunable filters to the wavelengths used on the input fiber links. 
     
     
       12. The optical cross-connect node in claim 9, wherein the wavelength channels are switched in the optical cross-connect node without a space switch. 
     
     
       13. The optical cross-connect node in claim 9, wherein the wavelength converters are four wave mixing semiconductor optical amplifiers. 
     
     
       14. The optical cross-connect node in claim 9, wherein the optical cross-connect is connected to an electronic cross-connect through the optical couplers. 
     
     
       15. The optical cross-connect node in claim 9, wherein a new fiber link or a new wavelength channel is modularly added to the optical cross-connect node without disabling the optical cross-connect node. 
     
     
       16. The optical cross-connect node in claim 9, wherein one wavelength channel is routed by plural one of the tunable filters to plural output fiber links. 
     
     
       17. The optical cross-connect node in claim 16, wherein the one wavelength channel routed to plural output fiber links contains analog signals. 
     
     
       18. A method of adding a new fiber optic link to an existing, single stage optical cross-connect node that includes optical fiber input links and output links each containing plural wavelength channels; optical splitters, each optical splitter coupled to a corresponding one of the input links; optical star couplers coupled to each of the optical splitters, each optical star coupler having an input port for each input link; tunable optical filters, each connected to one of the optical couplers for selecting any one of the input wavelength channels received on any of the input links; optical wavelength converters, each corresponding and connected to a tunable optical filter and capable of translating the selected wavelength channel to a different wavelength channel; and optical combiners for combining selected wavelength channels generated by the wavelength converters onto corresponding optical fiber output links, comprising the steps of: coupling the new link to an available input port of one of the existing optical star couplers within the single stage or to input ports of optical star couplers newly added to the single stage;   coupling in the single stage an additional tunable filter and corresponding additional wavelength converter associated with each new wavelength channel carried on the new link to an available output port of each existing optical star coupler or to an output port of each newly added optical star coupler; and   connecting an output from the additional wavelength converter to an additional optical combiner added to the single stage.   
     
     
       19. The method in claim 18, further comprising: maintaining operation of the single stage optical cross connect node when the new link is being added.   
     
     
       20. A method of adding a new wavelength channel to an existing, single stage optical cross-connect node that includes optical fiber input links and output links each containing plural wavelength channels; optical splitters, each optical splitter coupled to a corresponding one of the input links; optical star couplers coupled to each of the optical splitters, each optical star coupler having an input port for each input link; tunable optical filters, each connected to one of the optical couplers for selecting any one of the input wavelength channels received on any of the input links; optical wavelength converters, each corresponding and connected to a tunable optical filter and capable of translating the selected wavelength channel to a different wavelength channel; and optical combiners for combining selected wavelength channels generated by the wavelength converters onto corresponding optical fiber output links, comprising the steps of: coupling in the single stage an additional tunable filter and corresponding additional wavelength converter associated with the new wavelength channel to an available output port of each existing optical star coupler or to an output port of each newly added optical star coupler; and   connecting an output from each additional wavelength converter to a corresponding optical combiner added to the single stage.   
     
     
       21. A method of adding a new fiber optic link to an existing optical cross-connect node that includes optical fiber input links and output links each containing plural wavelength channels; input wavelength converters, each connected to one of the input links and capable of converting a comb of plural wavelength channels to another comb of wavelength channels; optical couplers having an input port for each input link; tunable optical filters, each connected to one of the optical couplers for selecting a wavelength channel; output optical wavelength converters, each corresponding and connected to each tunable optical filter and capable of translating the selected wavelength channel to a different wavelength channel; and optical combiners for combining selected wavelength channels generated by the wavelength converters onto corresponding optical fiber output links, comprising the steps of: coupling the link through an additional input wavelength converter to an available input port of the existing optical couplers or to input ports of newly added optical couplers;   coupling an additional tunable filter and corresponding additional output wavelength converter associated with each new wavelength channel carried on the new link to an available output port of each existing optical coupler or to an output port of each newly added optical coupler; and   connecting an output from each additional wavelength converter to an additional optical combiner.   
     
     
       22. The method in claim 21, further comprising: maintaining operation of the optical cross-connect node when the new link is being added.   
     
     
       23. A method of adding a new wavelength channel to an existing optical cross-connect node that includes optical fiber input links and output links each containing plural wavelength channels; input wavelength converters, each connected to one of the input links and capable of converting a comb of plural wavelength channels to another comb of wavelength channels; optical couplers having an input port for each input link; tunable optical filters, each connected to one of the optical couplers for selecting a wavelength channel; output optical wavelength converters, each corresponding and connected to each tunable optical filter and capable of translating the selected wavelength channel to a different wavelength channel; and optical combiners for combining selected wavelength channels generated by the wavelength converters onto corresponding optical fiber output links, comprising the steps of: determining that a new wavelength channel is to be added to one of the input links;   coupling an additional tunable filter and corresponding additional output wavelength converter associated with the new wavelength channel to an available output port of the existing optical couplers or to an output port of each newly added optical coupler; and   connecting an output from each additional wavelength converter to a corresponding optical combiner.   
     
     
       24. A method of servicing an optical cross-connect node that includes optical fiber input links and output links each containing plural wavelength channels; input wavelength converters, each connected to one of the input links and capable of converting a comb of plural wavelength channels to another comb of wavelength channels; optical couplers having an input port for each input link; tunable optical filters, each connected to one of the optical couplers for selecting a wavelength channel; output optical wavelength converters, each corresponding and connected to each tunable optical filter and capable of translating the selected wavelength channel to a different wavelength channel; and optical combiners for combining selected wavelength channels generated by the wavelength converters onto corresponding optical fiber output links, comprising the steps of: disabling one of the optical links, optical couplers, tunable optical filters, wavelength converters, or optical combiners;   servicing the disabled one of the optical links, optical couplers, tunable optical filters, wavelength converters, or optical combiners; and   during the servicing step, maintaining operation of the optical cross-connect node by routing information using an enabled optical link, optical coupler, tunable filter, wavelength converter, and optical combiner.